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BIOL 314 Exam 4 > Pregnancy and Birth > Flashcards

Pregnancy and Birth Flashcards

1
Q

fertilization

A

the union of a sperm with an egg to form a zygote

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2
Q

fertilization typically occurs in

A

the ampulla of a Fallopian tube

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3
Q

semen is deposited into the vagina as a liquid, but

A

fibrinogenase converts fibrinogen into a fibrin clot within one minute to prevent semen from leaking out of the vagina, and also to protect the sperm from the acidity of the vagina

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4
Q

after about 20 minutes,

A

vaginal acidity in neutralized and sperm can survive so semen clot liquefies

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5
Q

of the several hundred million sperm ejaculated into vagina,

A

fewer than 1% survive

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6
Q

the cervix contains a maze of

A

folds and outpocketings that can easily trap sperm

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7
Q

shortly before ovulation,

A

cervical mucus becomes thinner to facilitate passage of sperm through cervix

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8
Q

approx one million sperm survive

A

journey through cervix

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9
Q

the uterine cavity is filled with

A

a watery fluid through which sperm can easily pass

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10
Q

only a few thousand sperm survive to enter the Fallopian tubes and

A

they move through the Fallopian tubes assisted by ciliary action

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11
Q

only 50 to 100 sperm will actually reach

A

a secondary oocyte

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12
Q

sperm appear to be drawn toward

A

an oocyte by some type of chemical communication, but before they can fertilize an oocyte they must undergo capacitation

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13
Q

capacitation probably removes

A

a protective coating from head of a sperm that blocks release of acrosome enzymes needed for penetration of secondary oocyte

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14
Q

when sperm approach a secondary oocyte,

A

small openings form in the acrosome which allows enzymes to escape and digest a path for sperm to enter into the secondary oocyte

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15
Q

the secondary oocyte responds to sperm penetration by

A

blocking entry of more than one sperm, which prevents polyspermy from occuring

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16
Q

cortical granules inside membrane of

A

secondary oocyte are released

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17
Q

secondary oocyte completes

A

second meiotic division to produce ovum and polar body

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18
Q

the sperm fuses with the ovum to produce

A

a zygote and the chromosomes unite, which restores the diploid condition

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19
Q

secondary oocyte will degenerate within 24 hours of

A

ovulation unless it is fertilized

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20
Q

sperm can survive in female reproductive tract for

A

7 days so fertilization can occur during a one week “window of opportunity” around time of ovulation

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21
Q

if two oocytes are released during ovulation and each gets penetrated by a separate sperm,

A

two eggs may be fertilized and dizygotic (fraternal) twins result

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22
Q

approx 30 hours after fertilization,

A

the zygote divides by mitosis and forms two identical daughter cells

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23
Q

mitotic divisions continue to occur every

A

16 to 20 hours, which produces a collection of blastomeres that form a solid morula

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24
Q

these divisions occur quite rapidly and blastomeres

A

get progressively smaller, morula remains same size as original zygote

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25
Q

the cells of the morula become

A

tightly packed through compaction and blastomeres of unequal size begin to form, which creates hollow blastocyst

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26
Q

outer layer of smaller trophoblast cells form

A

layers around developing embryo

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27
Q

larger cells inside trophoblast make up

A

inner cell mass

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28
Q

if a single zygote separates completely during cleavage

A

monozygotic (identical) twins will result

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29
Q

implantation begins

A

when a blastocyst comes into contact with the endometrium

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30
Q

spontaneous abortions (miscarriages) may occur at this time because

A

2 out of every 3 blastocysts may not implant due to genetic abnormalities in embyro

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31
Q

as a blastocyst begins to implant,

A

cells of the trophoblast divide and differentiate and grow into the endometrium to anchor the blastocyst in place and the inner cell mass separates from the trophoblast and differentiates into the primary germ layers of the embryo

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32
Q

ectoderm will form

A

skin, hair, nails, neural tissue, and linings of mouth and throat

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33
Q

mesoderm will form

A

bone, cartilage, muscle, and parts of heart, kidneys, and gonads

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34
Q

endoderm will form

A

most of gut and parts of liver and pancreas, linings of digestive tract and respiratory, and reproductive ducts

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35
Q

four extraembryonic membranes form from the

A

primary germ layers of the embryo

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36
Q

yolk sac develops from

A

endoderm and mesoderm to form embryonic blood until liver is established

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37
Q

amnion develops from

A

ectoderm and mesoderm to surround embryo

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38
Q

amniotic sac fills with

A

amniotic fluid which cushions and protects developing embryo; also maintains constant temp and pressure

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39
Q

allantois

A

develops from endoderm near base of yolk sac; contributes to development of urinary bladder

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40
Q

blood vessels in the allantois

A

become umbilical vein and umbilical arteries

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41
Q

chorion

A

develops from mesoderm and forms finger-like chorionic villi that penetrate endometrium to establish network of blood vessels

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42
Q

the placenta forms in part from

A

maternal tissue and in part from embryonic tissue

43
Q

chorionic villi contain

A

blood vessels and grow into the endometrium, where they get surrounded by maternal blood sinuses to form the placenta

44
Q

placenta serves as

A

a selectively permeable barrier between maternal bloodstream and embryonic bloodstream

45
Q

blood is never

A

exchanged and materials “cross the placenta” by simple diffusion

46
Q

umbilical cord

A

the amnion fuses with the chorion and they surround the allantoic vessels to form an umbilical cord

47
Q

umbilical cord attaches belly of

A

embryo to middle of placenta

48
Q

umbilical cord contains

A

two umbilical arteries and one umbilical vein

49
Q

umbilical vein

A

carries blood that is rich in oxygen and nutrients from placenta to embryo/fetus

50
Q

umbilical arteries

A

carry blood that contains carbon dioxide and wastes from embryo/fetus to placenta to be eliminated

51
Q

placenta produces

A

several hormones that are needed to maintain pregnancy

52
Q

a full term pregnancy lasts for approximately

A

9 months, or 40 weeks or 266 days and can be divided into two major periods

53
Q

embryonic stage

A

typically refers to first 8 weeks of gestation; characterized by development of major organ systems in embryo

54
Q

fetal stage

A

typically refers to the last 30-32 weeks of gestation; characterized by organ growth and maturation of fetus

55
Q

the corpus luteum in the ovary

A

secretes estrogens and progesterone to maintain the endometrium and prepare the mammary glands for lactation

56
Q

chorionic villi secrete

A

human chorionic gonadotropin (hCG) to maintain the corpus luteum, which prevents menstruation that would eliminate the developing embryo

57
Q

hCG levels in the urine

A

serve as basis for home pregnancy tests

58
Q

hCG levels may be cause of

A

nausea and vomiting associated with morning sickness during first trimester of pregnancy

59
Q

the placenta eventually secretes

A

hormones that are needed to maintain the pregnancy

60
Q

the exact trigger of labor and birth

A

is not known, but various hormones are involved

61
Q

steroid hormones

A

released by fetus from cortex of its adrenal gland

62
Q

falling progesterone levels

A

increase sensitivity of uterine smooth muscles to oxytocin (near end of gestation)

63
Q

oxytocin

A

released from the posterior lobe of the pituitary gland to stimulate uterine smooth muscle to contract

64
Q

rising levels of oxytocin

A

stimulate production of prostaglandins that also contribute to uterine smooth muscle contractions

65
Q

relaxin

A

produced by placenta to soften pubic symphysis and dilate cervix

66
Q

2-3 weeks before labor begins

A

the fetus drops lower into the pelvic cavity in a process called “lightening” which reduces the pressure on the mother’s abdomen and diaphragm making it easier for her to breathe

67
Q

during the last week of gestation

A

the fetus will rotate in the uterus in order to present itself for delivery

68
Q

the head of fetus

A

usually moves into the cervix in order to exit first

69
Q

during the final weeks of gestation

A

a woman may experience “false labor” characterized by Braxton-Hick’s contractions that are regular and not very strong

70
Q

true labor is characterized by

A

contractions that become stronger at regular intervals

71
Q

Stage I of birth involves

A

cervical effacement and dilation and lasts from 4-24 hours

72
Q

cervix during birth

A

relatively inflexible and must retract upward to expose fetus’s head

73
Q

cervical canal during birth

A

has been blocked by a mucus plug during gestation; removal of plug creates bloody discharge into vagina

74
Q

amniotic sac during birth

A

ruptures, giving rise to expression “having the water break”

75
Q

contractions during birth

A

occur at short intervals and intensity as cervix completely dilates

76
Q

Stage II of birth involves

A

the expulsion of the fetus and lasts from 15 minutes to 2 hours

77
Q

contractions during stage II

A

reach maximum intensity at 1-2 minutes intervals

78
Q

head of the fetus during stage Ii

A

rotates from side-facing to downward facing and extends forward to pass beneath pubic bone

79
Q

once the head clears the birth canal

A

shoulders and rest of body slide past pubic bone

80
Q

crowning

A

appearance of head of fetus outside the birth canal

81
Q

episiotomy

A

may be performed if vaginal canal is too small to permit passage of fetus or if there is danger of perineal tearing

82
Q

incision of episiotomy

A

made from vagina to anus; can be repaired with sutures and will heal much faster than uncontrolled perineal tearing

83
Q

cesarean section

A

if complications occur during delivery, cesarean section can be performed

84
Q

breech birth

A

feet would be delivered first or umbilical cord could become tangled around baby’s neck

85
Q

size of baby- need for cesarean section

A

baby might be too large to be delivered vaginally

86
Q

placenta might detach

A

prematurely, which could cause uterine hemorrhage

87
Q

stage II involves

A

expulsion of the placenta within 15-30 minutes after parturition

88
Q

uterine contractions during stage III

A

tear placenta from endometrium to expel “afterbirth”

89
Q

forceful contractions constrict (during stage III)

A

uterine blood vessles to reduce hemorrhage

90
Q

actual milk production is stimulated by

A

the hormone prolactin (PRL)

91
Q

high levels of estrogens and progesterone during pregnancy

A

cause hypothalamus to release prolactin-inhibiting hormone (PIH); blocks secretion of prolactin

92
Q

without prolactin

A

mammary glands cannot produce milk

93
Q

elimination of the plcenta during afterbirth

A

reduces levels of estrogens and progesterone and allows prolactin to stimulate alveoli in breasts to produce milk

94
Q

the principal stimulus that maintains milk production

A

the sucking action of the infant

95
Q

sensory nerve endings in the nipple

A

activated by sucking and send signals to hypothalamus so more prolactin is relased’ promotes production and secretion of milk from alveoli into mammary ducts

96
Q

sucking also triggers

A

the milk-ejection reflex (milk letdown)

97
Q

sensory nerves in the nipples send signals to

A

hypothalamus to release oxytocin

98
Q

oxytocin stimulates contractions of

A

myoepithelial cells along lactiferous ducts to pump milk from alveoli through ducts and into nipple

99
Q

“milk letdown” can become

A

a conditioned reflex; nursing mother may find that hearing her baby cry or seeing her baby suck its thumb triggers release of milk

100
Q

the first liquid produced by the mammary glands

A

colostrum- a yellowish fluid that is high in protein but lower in lactose and fat than milk

101
Q

colostrum contains

A

important antibodies and iron-binding proteins

102
Q

breast feeding maintains

A

higher levels of oxytocin in a mother’s bloodstream, which causes contractions of uterine smooth muscles that can help restore the uterus to its pre-pregnant state

103
Q

breast feeding may provide

A

natural contraception for some women because nursing will reduce GnRH secretion by the hypothalamus, which reduces the amount of FSH and LH released by the pituitary gland

104
Q

reduction in FSH and LH will

A

inhibit follicle development and ovulation

BIOL 314 Exam 4 (13 decks)

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